docs: def _iter_rawterms(cls, tree):
          """Iterate through the raw terms (Classes) in the ontology.
          """
          for elem in tree.iterfind(OWL_CLASS):
              if RDF_ABOUT not in elem.keys():   # This avoids parsing a class
                  continue                       # created by restriction
              rawterm = cls._extract_resources(elem)
              rawterm['id'] = cls._get_id_from_url(elem.get(RDF_ABOUT))
              yield rawterm